Differential Participation of Plant Ribosomal Proteins from the Small Ribosomal Subunit in Protein Translation under Stress.

Upon exposure to biotic and abiotic stress, plants have developed strategies to adapt to the challenges imposed by these unfavorable conditions. The energetically demanding translation process is one of the main elements regulated to reduce energy consumption and to selectively synthesize proteins involved in the establishment of an adequate response. Emerging data have shown that ribosomes remodel to adapt to stresses. In Arabidopsis thaliana, ribosomes consist of approximately eighty-one distinct ribosomal proteins (RPs), each of which is encoded by two to seven genes. Recent research has revealed that a mutation in a given single RP in plants can not only affect the functions of the RP itself but can also influence the properties of the ribosome, which could bring about changes in the translation to varying degrees. However, a pending question is whether some RPs enable ribosomes to preferentially translate specific mRNAs. To reveal the role of ribosomal proteins from the small subunit (RPS) in a specific translation, we developed a novel approach to visualize the effect of RPS silencing on the translation of a reporter mRNA (GFP) combined to the 5'UTR of different housekeeping and defense genes. The silencing of genes encoding for NbRPSaA, NbRPS5A, and NbRPS24A in Nicotiana benthamiana decreased the translation of defense genes. The NbRACK1A-silenced plant showed compromised translations of specific antioxidant enzymes. However, the translations of all tested genes were affected in NbRPS27D-silenced plants. These findings suggest that some RPS may be potentially involved in the control of protein translation.

Migration of Small Ribosomal Subunits on the 5' Untranslated Regions of Capped Messenger RNA.

Several control mechanisms of eukaryotic gene expression target the initiation step of mRNA translation. The canonical translation initiation pathway begins with cap-dependent attachment of the small ribosomal subunit (SSU) to the messenger ribonucleic acid (mRNA) followed by an energy-dependent, sequential 'scanning' of the 5' untranslated regions (UTRs). Scanning through the 5'UTR requires the adenosine triphosphate (ATP)-dependent RNA helicase eukaryotic initiation factor (eIF) 4A and its efficiency contributes to the specific rate of protein synthesis. Thus, understanding the molecular details of the scanning mechanism remains a priority task for the field. Here, we studied the effects of inhibiting ATP-dependent translation and eIF4A in cell-free translation and reconstituted initiation reactions programmed with capped mRNAs featuring different 5'UTRs. An aptamer that blocks eIF4A in an inactive state away from mRNA inhibited translation of capped mRNA with the moderately structured ß-globin sequences in the 5'UTR but not that of an mRNA with a poly(A) sequence as the 5'UTR. By contrast, the nonhydrolysable ATP analogue ß,γ-imidoadenosine 5'-triphosphate (AMP-PNP) inhibited translation irrespective of the 5'UTR sequence, suggesting that complexes that contain ATP-binding proteins in their ATP-bound form can obstruct and/or actively block progression of ribosome recruitment and/or scanning on mRNA. Further, using primer extension inhibition to locate SSUs on mRNA ('toeprinting'), we identify an SSU complex which inhibits primer extension approximately eight nucleotides upstream from the usual toeprinting stop generated by SSUs positioned over the start codon. This '-8 nt toeprint' was seen with mRNA 5'UTRs of different length, sequence and structure potential. Importantly, the '-8 nt toeprint' was strongly stimulated by the presence of the cap on the mRNA, as well as the presence of eIFs 4F, 4A/4B and ATP, implying active scanning. We assembled cell-free translation reactions with capped mRNA featuring an extended 5'UTR and used cycloheximide to arrest elongating ribosomes at the start codon. Impeding scanning through the 5'UTR in this system with elevated magnesium and AMP-PNP (similar to the toeprinting conditions), we visualised assemblies consisting of several SSUs together with one full ribosome by electron microscopy, suggesting direct detection of scanning intermediates. Collectively, our data provide additional biochemical, molecular and physical evidence to underpin the scanning model of translation initiation in eukaryotes.

Impaired Ribosomal Biogenesis by Noncanonical Degradation of ß-Catenin during Hyperammonemia.

Increased ribosomal biogenesis occurs during tissue hypertrophy, but whether ribosomal biogenesis is impaired during atrophy is not known. We show that hyperammonemia, which occurs in diverse chronic disorders, impairs protein synthesis as a result of decreased ribosomal content and translational capacity. Transcriptome analyses, real-time PCR, and immunoblotting showed consistent reductions in the expression of the large and small ribosomal protein subunits (RPL and RPS, respectively) in hyperammonemic murine skeletal myotubes, HEK cells, and skeletal muscle from hyperammonemic rats and human cirrhotics. Decreased ribosomal content was accompanied by decreased expression of cMYC, a positive regulator of ribosomal biogenesis, as well as reduced expression and activity of ß-catenin, a transcriptional activator of cMYC. However, unlike the canonical regulation of ß-catenin via glycogen synthase kinase 3ß (GSK3ß)-dependent degradation, GSK3ß expression and phosphorylation were unaltered during hyperammonemia, and depletion of GSK3ß did not prevent ammonia-induced degradation of ß-catenin. Overexpression of GSK3ß-resistant variants, genetic depletion of IκB kinase ß (IKKß) (activated during hyperammonemia), protein interactions, and in vitro kinase assays showed that IKKß phosphorylated ß-catenin directly. Overexpressing ß-catenin restored hyperammonemia-induced perturbations in signaling responses that regulate ribosomal biogenesis. Our data show that decreased protein synthesis during hyperammonemia is mediated via a novel GSK3ß-independent, IKKß-dependent impairment of the ß-catenin-cMYC axis.

Odilorhabdins, Antibacterial Agents that Cause Miscoding by Binding at a New Ribosomal Site.

Growing resistance of pathogenic bacteria and shortage of antibiotic discovery platforms challenge the use of antibiotics in the clinic. This threat calls for exploration of unconventional sources of antibiotics and identification of inhibitors able to eradicate resistant bacteria. Here we describe a different class of antibiotics, odilorhabdins (ODLs), produced by the enzymes of the non-ribosomal peptide synthetase gene cluster of the nematode-symbiotic bacterium Xenorhabdus nematophila. ODLs show activity against Gram-positive and Gram-negative pathogens, including carbapenem-resistant Enterobacteriaceae, and can eradicate infections in animal models. We demonstrate that the bactericidal ODLs interfere with protein synthesis. Genetic and structural analyses reveal that ODLs bind to the small ribosomal subunit at a site not exploited by current antibiotics. ODLs induce miscoding and promote hungry codon readthrough, amino acid misincorporation, and premature stop codon bypass. We propose that ODLs' miscoding activity reflects their ability to increase the affinity of non-cognate aminoacyl-tRNAs to the ribosome.

Phylogeny of the families Zoothamniidae and Epistylididae (Protozoa: Ciliophora: Peritrichia) based on analyses of three rRNA-coding regions.

Peritrichs are a major group of ciliates with worldwide distribution, and they play important roles in many habitats. Intrafamilial phylogeny of some peritrichs was investigated using information from three genes, which provided more robust interpretations than single-gene analyses. Sixty-seven new sequences including SSU rDNA, ITS1-5.8S-ITS2 and LSU rDNA were aligned with available sequences in GenBank to infer phylogenetic relationships within the families Zoothamniidae and Epistylididae. Results reveal the following relationships: (1) Epistylididae is polyphyletic, consisting of two clades that nest within the Zoothamniidae as part of the crown clade of peritrichs (order Vorticellida) and a third one that is part of the basal clade of peritrichs (order Opercularida); (2) Epistylis elongata falls within one of the clades of Zoothamnium rather than with congeners; (3) Zoothamnium is probably paraphyletic, consisting of three divergent clades, with the genera Myoschiston and Zoothamnopsis intermingled with species of Zoothamnium. The following evolutionary hypotheses can be inferred from these results: (1) the contractile stalk of Zoothamnium is plesiomorphic. (2) Myoschiston, Zoothamnopsis and clade II of Epistylididae are derived from the Zoothamnium morphotype by partial or incomplete development of the spasmoneme that forms the contractile center of the stalk around which the rigid cortex is secreted. (3) Clade I of the Epistylididae, which are primarily colonial forms that appear never to have evolved a spasmoneme of any sort, may represent the ancestral morphotype of peritrichs.

Cystic echinococcosis in Poland: genetic variability and the first record of Echinococcus granulosus sensu stricto (G1 genotype) in the country.

Cystic echinococcosis is one of the most important zoonotic diseases affecting humans and livestock worldwide, and is endemic in Poland. A set of six isolates on larval stages of Echinococcus granulosus sensu lato tapeworms collected from three humans, two pigs and one sheep from Polish foci of CE was examined by DNA sequencing of two mitochondrial genes (cox1, rrnS). The results demonstrated the presence of E. canadensis and E. granulosus sensu stricto in the investigated hydatid cysts. The former species was found in all five isolates from pigs and humans derived from central Poland. In a sheep hydatid cyst originating from Lesser Poland Voivodeship in southern Poland, E. granulosus s. s. (G1 genotype) was identified. This is the first report of an unambiguously autochthonous infection with E. granulosus s. s. in Poland. The global distribution and host affiliations of the commonly occurring G1 microvariant with nucleotide change 56C/T in cox1, detected here in Polish sheep, are discussed. The finding that sheep harboured E. granulosus s. s. may have important consequences for developing effective hydatid control programmes in Poland due to its longer maturation rate in dogs compared with E. canadensis G7. This may lead to greater expenditures for purchasing anthelmintics to provide an appropriate dosing regime in sheep-raising areas of the country.

Taxonomy and Phylogeny of Polyporus Group Melanopus (Polyporales, Basidiomycota) from China.

Melanopus is a morphological group of Polyporus which contains species with a black cuticle on the stipe. In this article, taxonomic and phylogenetic studies on Melanopus group were carried out on the basis of morphological characters and phylogenetic evidence of DNA sequences of multiple loci including the internal transcribed spacer (ITS) regions, the large subunit nuclear ribosomal RNA gene (nLSU), the small subunit nuclear ribosomal RNA gene (nSSU), the small subunit mitochondrial rRNA gene sequences (mtSSU), the translation elongation factor 1-α gene (EF1-α), the largest subunit of RNA polymerase II (RPB1), the second largest subunit of RNA polymerase II (RPB2), and ß-tubulin gene sequences (ß-tubulin). The phylogenetic result confirmed that the previously so-called Melanopus group is not a monophyletic assemblage, and species in this group distribute into two distinct clades: the Picipes clade and the Squamosus clade. Four new species of Picipes are described, and nine new combinations are proposed. A key to species of Picipes is provided.

Ultrastructure and phylogeny of Kudoa barracudai sp. nov. infecting Sphyraena putnamae in the Red Sea.

Kudoa barracudai n. sp. has been found infecting the muscles of Sphyraena putnamae from Red Sea, Saudi Arabia. The prevalence of the infection was 10 % (5/50). Its ovoidal plasmodia encapsulated with fibrous connective tissue and measuring 700 × 510 µm. Local myolysis was observed around the plasmodia without inflammatory reaction. Mature spores were quadrate in the apical view with rounded edges and subspherical to ovoid in the side view and measured 5 µm (4.5-5.5) in width and 5.5 µm (5-6) in thickness. Polar capsules were pyriform, equal in size, and measured 2.5 µm (2-3) in length and 1.5 µm (1-2) in width with two filament coils. Ultrastructural analysis showed a demarcated border between the parasite cellular mass and host cellular components that represented the cyst wall, and cysts were filled with mostly mature spores. Phylogenetic analysis of the small subunit ribosomal RNA (SSU rRNA) using the maximum likelihood and Bayesian inference approaches showed the new species clustered in a robust clade with Kudoa amamiensis, Kudoa kenti, and Kudoa quraishii. The SSU rRNA gene of K. barracudai was most similar to K. amamiensis (98.7 %), followed by K. kenti (97.4 %) and K. quraishii (96.6 %). This combination of morphological data and molecular analysis served to identify this parasite as a new species of Kudoa, which we have named K. barracudai n. sp.

Ribosome-associated pentatricopeptide repeat proteins function as translational activators in mitochondria of trypanosomes.

Mitochondrial ribosomes of Trypanosoma brucei are composed of 9S and 12S rRNAs, eubacterial-type ribosomal proteins, polypeptides lacking discernible motifs and approximately 20 pentatricopeptide repeat (PPR) RNA binding proteins. Several PPRs also populate the polyadenylation complex; among these, KPAF1 and KPAF2 function as general mRNA 3' adenylation/uridylation factors. The A/U-tail enables mRNA binding to the small ribosomal subunit and is essential for translation. The presence of A/U-tail also correlates with requirement for translation of certain mRNAs in mammalian and insect parasite stages. Here, we inquired whether additional PPRs activate translation of individual mRNAs. Proteomic analysis identified KRIPP1 and KRIPP8 as components of the small ribosomal subunit in mammalian and insect forms, but also revealed their association with the polyadenylation complex in the latter. RNAi knockdowns demonstrated essential functions of KRIPP1 and KRIPP8 in the actively respiring insect stage, but not in the mammalian stage. In the KRIPP1 knockdown, A/U-tailed mRNA encoding cytochrome c oxidase subunit 1 declined concomitantly with the de novo synthesis of this subunit whereas polyadenylation and translation of cyb mRNA were unaffected. In contrast, the KRIPP8 knockdown inhibited A/U-tailing and translation of both CO1 and cyb mRNAs. Our findings indicate that ribosome-associated PPRs may selectively activate mRNAs for translation.

Small subunit ribosomal RNA sequence links the myxospore stage of Henneguya mississippiensis n. sp. from channel catfish Ictalurus punctatus to an actinospore released by the benthic oligochaete Dero digitata.

There are more than 200 species of Henneguya described from fish. Of these, only three life cycles have been determined, identifying the actinospore and myxospore stages from their respective hosts. Two of these life cycles involve the channel catfish (Ictalurus punctatus) and the freshwater oligochaete Dero digitata. Herein, we molecularly confirm the life cycle of a previously undescribed Henneguya sp. by matching 18S ribosomal RNA (rRNA) gene sequence of the myxospore stage from channel catfish with the previously described actinospore stage (Aurantiactinomyxon mississippiensis) from D. digitata. Gill tissue from naturally infected channel catfish contained pseudocysts restricted to the apical end of the primary lamellae. Myxospores were morphologically consistent with Henneguya spp. from ictalurid fishes in North America. The spores measured 48.8 ± 4.8 µm (range = 40.7-61.6 µm) in total spore length. The lanceolate spore body was 17.1 ± 1.0 µm (14.4-19.3 µm) in length and 5.0 ± 0.3 µm (4.5-5.5 µm) in width. The two polar capsules were 6.2 ± 0.4 µm (5.8-7.0 µm) long and 5.0 ± 0.3 µm (4.5-5.5 µm) wide. The polar capsule contained eight to nine coils in the polar filament. The two caudal processes were of equal length, measuring 31.0 ± 4.1 µm (22.9-40.6 µm). The 1980-bp 18S rRNA gene sequence obtained from two excised cysts shared 99.4% similarity (100% coverage) to the published sequence of A. mississippiensis, an actinospore previously described from D. digitata. The sequence similarity between the myxospore from channel catfish and actinospore from D. digitata suggests that they are conspecific, representing alternate life stages of Henneguya mississippiensis n. sp.

New insights into the molecular phylogeny of Balantidium (Ciliophora, Vetibuliferida) based on the analysis of new sequences of species from fish hosts.

We obtained sequences of the small subunit ribosomal RNA (rRNA) for two new isolates of Balantidium from fishes, Balantidium polyvacuolum and Balantidium ctenopharingodoni. This is the first introduction of molecular data of Balantidium species from fish hosts in the phylogenetic analyses of the ciliate subclass Trichostomatia. Despite the fact that these species share morphological characteristics common to other species of Balantidium, the phylogenetic analysis of their sequences has shown that they are to be placed in a different branch closely related to the so-called Australian clade. Thus, our results indicate that the genus Balantidium is polyphyletic and possibly should be represented by two different genera; however, the analysis of more species from other poikilothermic hosts (amphibians, reptiles) should be made before a revised taxonomical proposal could be made.

Plastid mRNA translation.

Overall translational machinery in plastids is similar to that of E. coli. Initiation is the crucial step for translation and this step in plastids is somewhat different from that of E. coli. Unlike the Shine-Dalgarno sequence in E. coli, cis-elements for translation initiation are not well conserved in plastid mRNAs. Specific trans-acting factors are generally required for translation initiation and its regulation in plastids. During translation elongation, ribosomes pause sometimes on photosynthesis-related mRNAs due probably to proper insertion of nascent polypeptides into membrane complexes. Codon usage of plastid mRNAs is different from that of E. coli and mammalian cells. Plastid mRNAs do not have the so-called rare codons. Translation efficiencies of several synonymous codons are not always correlated with codon usage in plastid mRNAs.

Human diseases of the SSU processome.

Ribosomes are the cellular machines responsible for protein synthesis. Ribosome biogenesis, the production of ribosomes, is a complex process involving pre-ribosomal RNA (rRNA) cleavages and modifications as well as ribosomal protein assembly around the rRNAs to create the functional ribosome. The small subunit (SSU) processome is a large ribonucleoprotein (RNP) in eukaryotes required for the assembly of the SSU of the ribosome as well as for the maturation of the 18S rRNA. Despite the fundamental nature of the SSU processome to the survival of any eukaryotic cell, mutations in SSU processome components have been implicated in human diseases. Three SSU processome components and their related human diseases will be explored in this review: hUTP4/Cirhin, implicated in North American Indian childhood cirrhosis (NAIC); UTP14, implicated in infertility, ovarian cancer, and scleroderma; and EMG1, implicated in Bowen-Conradi syndrome (BCS). Diseases with suggestive, though inconclusive, evidence for the involvement of the SSU processome in their pathogenesis are also discussed, including a novel putative ribosomopathy. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease.

Sphaerospora sensu stricto: taxonomy, diversity and evolution of a unique lineage of myxosporeans (Myxozoa).

Myxosporeans (Myxozoa) are eukaryotic parasites, primarily of fish, whose classification is in a state of flux as taxonomists attempt to synthesize the traditional morphology-based system with emerging DNA sequence-based phylogenies. The genus Sphaerospora Thélohan, 1892, which includes pathogenic species that cause significant impacts on fisheries and aquaculture, is one of the most polyphyletic taxa and exemplifies the current challenges facing myxozoan taxonomists. The type species, S. elegans, clusters within the Sphaerospora sensu stricto clade, members of which share similar tissue tropism and long insertions in their variable rRNA gene regions. However, other morphologically similar sphaerosporids lie in different branches of myxozoan phylogenetic trees. Herein, we significantly extend taxonomic sampling of sphaerosporids with SSU+LSU rDNA and EF-2 sequence data for 12 taxa including three representatives of the morphologically similar genus Polysporoplasma Sitjà-Bobadilla et Álvarez-Pellitero, 1995. These taxa were sampled from different vertebrate host groups, biogeographic realms and environments. Our phylogenetic analyses and statistical tests of single and concatenated datasets revealed Sphaerospora s. s. as a strongly supported monophyletic lineage, that clustered sister to the whole myxosporean clade (freshwater+marine lineages). Generally, Sphaerospora s. s. rDNA sequences (up to 3.7 kb) are the longest of all myxozoans and indeed metazoans. The sphaerosporid clade has two lineages, which have specific morphological, biological and sequence traits. Lineage A taxa (marine Sphaerospora spp.) have a single binucleate sporoplasm and shorter AT-rich rDNA inserts. Lineage B taxa (freshwater/brackish Sphaerospora spp.+marine/brackish Polysporoplasma spp.) have 2-12 uninucleate sporoplasms and longer GC-rich rDNA inserts. Lineage B has four subclades that correlate with host group and habitat; all Polysporoplasma species, including the type species, cluster together in one of these subclades. We thus suppress the genus Polysporoplasma and the family Polysporoplasmidae and emend the generic diagnosis of the genus Sphaerospora. The combination of morphological, biological and DNA sequence data applied in this study helped to elucidate an important part of the taxonomic puzzle within the phylum Myxozoa.

MRPS27 is a pentatricopeptide repeat domain protein required for the translation of mitochondrially encoded proteins.

Mammalian pentatricopeptide repeat domain (PPR) proteins are involved in regulation of mitochondrial RNA metabolism and translation and are required for mitochondrial function. We investigated an uncharacterised PPR protein, the supernumerary mitochondrial ribosomal protein of the small subunit 27 (MRPS27), and show that it associates with the 12S rRNA and tRNA(Glu), however it does not affect their abundance. We found that MRPS27 is not required for mitochondrial RNA processing or the stability of the small ribosomal subunit. However, MRPS27 is required for mitochondrial protein synthesis and its knockdown causes decreased abundance in respiratory complexes and cytochrome c oxidase activity.

Identification of methylated proteins in the yeast small ribosomal subunit: a role for SPOUT methyltransferases in protein arginine methylation.

We have characterized the posttranslational methylation of Rps2, Rps3, and Rps27a, three small ribosomal subunit proteins in the yeast Saccharomyces cerevisiae, using mass spectrometry and amino acid analysis. We found that Rps2 is substoichiometrically modified at arginine-10 by the Rmt1 methyltransferase. We demonstrated that Rps3 is stoichiometrically modified by ω-monomethylation at arginine-146 by mass spectrometric and site-directed mutagenic analyses. Substitution of alanine for arginine at position 146 is associated with slow cell growth, suggesting that the amino acid identity at this site may influence ribosomal function and/or biogenesis. Analysis of the three-dimensional structure of Rps3 in S. cerevisiae shows that arginine-146 makes contacts with the small subunit rRNA. Screening of deletion mutants encoding potential yeast methyltransferases revealed that the loss of the YOR021C gene results in the absence of methylation of Rps3. We demonstrated that recombinant Yor021c catalyzes ω-monomethylarginine formation when incubated with S-adenosylmethionine and hypomethylated ribosomes prepared from a YOR021C deletion strain. Interestingly, Yor021c belongs to the family of SPOUT methyltransferases that, to date, have only been shown to modify RNA substrates. Our findings suggest a wider role for SPOUT methyltransferases in nature. Finally, we have demonstrated the presence of a stoichiometrically methylated cysteine residue at position 39 of Rps27a in a zinc-cysteine cluster. The discovery of these three novel sites of protein modification within the small ribosomal subunit will now allow for an analysis of their functional roles in translation and possibly other cellular processes.

Taxonomy of fungi causing mucormycosis and entomophthoramycosis (zygomycosis) and nomenclature of the disease: molecular mycologic perspectives.

Molecular phylogenetic analysis confirmed the phylum Zygomycota to be polyphyletic, and the taxa conventionally classified in Zygomycota are now distributed among the new phylum Glomeromycota and 4 subphyla incertae sedis (uncertain placement). Because the nomenclature of the disease zygomycosis was based on the phylum Zygomycota (Zygomycetes) in which the etiologic agents had been classified, the new classification profoundly affects the name of the disease. Zygomycosis was originally described as a convenient and inclusive name for 2 clinicopathologically different diseases, mucormycosis caused by members of Mucorales and entomophthoramycosis caused by species in the order Entomophthorales of Zygomycota. Without revision of original definition, the name "zygomycosis," however, has more often been used as a synonym only for mucormycosis. This article reviews the progress and changes in taxonomy and nomenclature of Zygomycota and the disease zygomycosis. The article also reiterates the reasons why the classic names "mucormycosis" and "entomophthoramycosis" are more appropriate than "zygomycosis."

Hepatospora eriocheir (Wang and Chen, 2007) gen. et comb. nov. infecting invasive Chinese mitten crabs (Eriocheir sinensis) in Europe.

We describe a microsporidian parasite infecting non-native Chinese mitten crabs (Eriochier sinensis) from Europe. Electron microscopy revealed merogonic and sporogonic life stages bound within a plasmalemma. The crab parasite develops polar tube precursors at the sporont stage but does not complete formation of the intact spore extrusion apparatus at the stage of the sporogonial plasmodium like Enterocytozoon bienuesi and other representatives of the Enterocytozoonidae. Its presence within an aquatic crustacean host, and a distinct molecular phylogeny based on partial small subunit ribosomal RNA (SSU rRNA) gene sequences also place it relatively close, though distinct to, existing genera within the Enterocytozoonidae. Consideration of morphological and phylogenetic characteristics of other hepatopancreas-infecting microsporidia from crustaceans suggests that certain ones (e.g. Enterospora canceri) are retained within the clade corresponding to the existing family Enterocytozoonidae, while others, including the parasite described here, may eventually be grouped in a sister taxon potentially of family rank. Based upon morphological and host similarity, it is likely that the parasite described here is the same as Endoreticulatus eriocheir (Wang and Chen, 2007), previously described from Chinese mitten crabs in Asia. However, using a combined taxonomic approach based upon morphological and phylogenetic data, we propose the formation of a new genus (Hepatospora) to replace the previous generic classification of the Asian parasite as Endoreticulatus. The microsporidian from the hepatopancreas of E. sinensis is named Hepatospora eriocheir (Wang and Chen, 2007) gen. et comb. nov. It is assumed that the parasite was introduced during initial invasions of this crab to Europe during the early 20th Century.

Evolution of the order Urostylida (Protozoa, Ciliophora): new hypotheses based on multi-gene information and identification of localized incongruence.

Previous systematic arrangement on the ciliate order Urostylida was mainly based on morphological data and only about 20% taxa were analyzed using molecular phylogenetic analyses. In the present investigation, 22 newly sequenced species for which alpha-tubulin, SSU rRNA genes or ITS1-5.8S-ITS2 region were sampled, refer to all families within the order. Following conclusions could be drawn: (1) the order Urostylida is not monophyletic, but a core group is always present; (2) among the family Urostylidae, six of 10 sequenced genera are rejected belonging to this family; (3) the genus Epiclintes is confirmed belonging to its own taxon; (4) the family Pseudokeronopsidae undoubtedly belongs to the core portion of urostylids; however, some or most of its members should be transferred to the family Urostylidae; (5) Bergeriellidae is confirmed to be a valid family; (6) the distinction of the taxon Acaudalia is not supported; (7) the morphology-based genus Anteholosticha is extremely polyphyletic; (8) ITS2 secondary structures of Pseudoamphisiella and Psammomitra are rather different from other urostylids; (9) partition addition bootstrap alteration (PABA) result shows that bootstrap values usually tend to increase as more gene partitions are included.

Increased sampling reveals novel lineages of Entamoeba: consequences of genetic diversity and host specificity for taxonomy and molecular detection.

To expand the representation for phylogenetic analysis, ten additional complete Entamoeba small-subunit rRNA gene sequences were obtained from humans, non-human primates, cattle and a tortoise. For some novel sequences no corresponding morphological data were available, and we suggest that these organisms should be referred to as ribosomal lineages (RL) rather than being assigned species names at present. To investigate genetic diversity and host specificity of selected Entamoeba species, a total of 91 new partial small subunit rRNA gene sequences were obtained, including 49 from Entamoeba coli, 18 from Entamoeba polecki, and 17 from Entamoeba hartmanni. We propose a new nomenclature for significant variants within established Entamoeba species. Based on current data we propose that the uninucleated-cyst-producing Entamoeba infecting humans is called Entamoeba polecki and divided into four subtypes (ST1-ST4) and that Entamoeba coli is divided into two subtypes (ST1-ST2). New hosts for several species were detected and, while host specificity and genetic diversity of several species remain to be clarified, it is clear that previous reliance on cultivated material has given us a misleading and incomplete picture of variation within the genus Entamoeba.